1. Field of the Invention
The present invention relates to a developing apparatus, an image forming apparatus and a process cartridge.
2. Description of the Related Art
As a developing apparatus to develop an electrostatic latent image formed on a photoconductor, there is a developing apparatus equipped with; a toner bearing member including a roller portion which supplies a toner in a developer container containing the toner; and a regulating member which contacts a surface of the toner bearing member and regulates an amount of the toner to be adhered.
In the developing apparatus where the adhered amount of the toner on the toner bearing member is regulated by the regulating member, the roller portion of the toner bearing member is arranged at a toner outlet of the developer container, and a shaft portion projected from both ends of the roller portion is rotatably supported by supporting walls provided on both sides of the developer container. Also, as for the regulating member, a lower edge of the regulating member is contacted by the roller portion of the toner bearing member such that a space between an upper edge of the toner outlet and an upper outer periphery of the toner bearing member is blocked.
In such a developing apparatus, to prevent toner leakage from the space between the outer periphery of the toner bearing member and the toner outlet, a development entrance sealing member which blocks a space between a lower edge of the toner outlet and a lower outer periphery of the roller portion of the toner bearing member is attached at a lower portion of the developer container. Also, to prevent toner leakage from both ends in a longitudinal direction of the toner bearing member, a development end sealing member (or simply a seal) which contacts the both ends of the toner bearing member surface as well as the both ends of the regulating member and the development entrance sealing member are arranged (for example, see Japanese Patent (JP-B) No. 3825939).
However, with such a sealing structure, the toner bearing member surface and the seal become sliding parts during rotation of the toner bearing member, causing frictional heat due to friction between the both members and melting a toner around them. Then, the melted toner is fixed on the regulating member and lifts the regulating member, and there has been a problem that a toner scatters from a gap between the lifted regulating member and the toner bearing member, resulting in an abnormal image. There has also been a problem that impurities generated by the toner bearing member surface and the seal contacting at the sliding parts inhibit normal image formation.
Accordingly, there currently is being asked to provide a developing apparatus which is able to prevent toner leakage as well as occurrence of abnormal image derived from a sealing structure.